The synthesis of Vitamin E, that is, .alpha.-tocopherol (5,7,8-trimethyltocol) in the past has been accomplished primarily by reacting trimethylhydroquinone (TMHQ) with iso-phytol (3,7,11,15-tetramethylhexadec-1-en-3-ol) in a condensation reaction with a catalyst.
The reaction is well known and has been practiced for many years. The related phytol (3,7,11,15-tetramethylhexadec-2-en-1-ol) has also been used in the reaction with trimethylhydroquinone and a catalyst to produce Vitamin E. A procedure with isophytol under relatively mild conditions to obtain a high yield was published in the Journal of Organic Chemistry, Vol. 36 (19), pp. 2910-12, Wehrli, Fryer & Metlesics.
The various routes to phytol and its isomers have been reviewed by Stalla-Bourdillon, Ind. Chim. Belg., 35, 13 (1970). With few exceptions, these routes utilize a C.sub.10 intermediate (natural or synthetic) and proceed to the C.sub.20 phytol or isophytol by sequential addition of various carbon units (C.sub.3 or less). The steps are numerous, and the syntheses are costly.